Need help with tank temperature (can't get it cooler)

[AndyinAtlanta]

So I have the Fluval Flex 32.5 gallon saltwater tank, which is important to know because the tank's light is in the hood (and only an inch away from the water). I'd like to add a second light (same that came with my tank, I believe its the Fluval Marine 3.0), but I'm struggling with my tank's temperatures and I think its due to the heat from the light. Some additional variables that may be worth considering:

• The tank is not directly in front of any windows or diffusers
• The house temperature is set around 73 degrees
• I'm using the Fluval heater recommended for the tank.

I'd like the tank to sit at around 78-79 degrees, but no matter what I do it always creeps into the 80-81 range. The only time I can get it down to 78 is after a water change, but after two-to-three days it shoots back up to 80-81. The Fluval heater is set to 75 degrees so I'm guessing its barely ever on. I left the heater off for six hours today (with the light still on) and it gained .5 degrees over that period of time. I put an ice cube in the tank (in a plastic bag) and it briefly went down .2 degrees, but it was only temporary and it started going back up (again, no heater on).

I don't believe my tank is big enough to add a cooler, but I'm trying to determine the source of that much heat. I understand the pumps and lights generate heat, but so much that they render the heater irrelevant? I see a lot of posts about people trying to gain more heat, but I'm over here struggling to lose some of it.

 

[2Wheelsonly]

Your house is fairly warm, mine never reaches above 69 and I still have issues with heat. How many powered devices are in the water? Also, are you sure your heater isn't broken? Ever since I moved to a controller to control my temps I noticed how inaccurate these built in temp monitors are. My controller shuts my heaters off at 78, my heaters are set to 79 but will continue to run if my controller lets them all the way to 81.

If you're upgrading lights have you thought about taking the canopy off and going with a typical reef tank light like a Radion hanging above the water? That will allow for more evaporation and surface air flow.

I would start to get used to the idea that the canopy has to go; air flow over the water surface and the lights higher up for more spread are key to cooling that thing down.

 

[AndyinAtlanta]

Your house is fairly warm, mine never reaches above 69 and I still have issues with heat. How many powered devices are in the water? Also, are you sure your heater isn't broken? Ever since I moved to a controller to control my temps I noticed how inaccurate these built in temp monitors are. My controller shuts my heaters off at 78, my heaters are set to 79 but will continue to run if my controller lets them all the way to 81.

If you're upgrading lights have you thought about taking the canopy off and going with a typical reef tank light like a Radion hanging above the water? That will allow for more evaporation and surface air flow.

I would start to get used to the idea that the canopy has to go; air flow over the water surface and the lights higher up for more spread are key to cooling that thing down.

Yeah, I've considered the option of moving to a mesh top and upgrading the lights. That might be the best option. I'm pretty sure the heater isn't malfunctioning as the temperatures go up even when it is unplugged.

House is well over 120 years old, so no way I could get the temperature much lower living in the South. At 73 the AC is running almost all day.

 

[Victor_C3]

Pumps might make a difference. What are you running?

I had a 500ish Eheim pump and upgrades it to a 900 GPH Eheim pump and it was enough to increase my temperature 4-5 degrees in the span of 6 hours on a 30 gallon tank. I also had a protein skimmer running with a Mag-5 as well. All of these pumps were submersible.

Switching to an external pump might make a difference. Same with powerheads.

 

[Copingwithpods]

What most people do with lids is add fans to promote evaporative cooling. With 2 80mm fans and a temperature controller that 78 degree goal is well within reach and for not that much coin. Only downside is you do have to cut into your hood.

 

[AndyinAtlanta]

Pumps might make a difference. What are you running?

I had a 500ish Eheim pump and upgrades it to a 900 GPH Eheim pump and it was enough to increase my temperature 4-5 degrees in the span of 6 hours on a 30 gallon tank. I also had a protein skimmer running with a Mag-5 as well. All of these pumps were submersible.

Switching to an external pump might make a difference. Same with powerheads.

I did just add a protein skimmer (that goes into the water at the back of the tank). That would add another pump to the water. And yes, the pump, powerhead, and protein skimmer motors are all in the water. I'm not a fan of the powerhead I have, so many buying one with the motor on the outside would help.

 

[AndyinAtlanta]

What most people do with lids is add fans to promote evaporative cooling. With 2 80mm fans and a temperature controller that 78 degree goal is well within reach and for not that much coin. Only downside is you do have to cut into your hood.

Good point. I think if temperatures start creeping past 82 I'll have no problem cutting a few holes.

 

[C. Eymann]

81 isnt bad per say, its 83 or more is where I start getting nervous.

Evaporative cooling capacity can be rather substantial, but will increase evap so an ato is a must.

How are you measuring your temperature if I may ask?

 

[Copingwithpods]

Good point. I think if temperatures start creeping past 82 I'll have no problem cutting a few holes.

I say do it now and avoid a potential disaster. If your AC unit ever goes out your tank will not stop at 82. I don't cool my home during the day as no one is home so my tank has 3 fans to cool it independently of what ever the room temperature is. Just a nice little backup and one less thing to worry about.

You can go down the powerhead rabbit hole but all pumps will heat the water, some more than others. The efficiency route is very costly.

 

[SebastianReefer]

Yeah, I've considered the option of moving to a mesh top and upgrading the lights. That might be the best option. I'm pretty sure the heater isn't malfunctioning as the temperatures go up even when it is unplugged.

House is well over 120 years old, so no way I could get the temperature much lower living in the South. At 73 the AC is running almost all day.

My wife has a biocube 32 gallon and we live in Florida what I did was I took a half inch pvc coupler one for each side and used a dremel to make the notch where the lid is and propped up the lid and I have a fan across the room that blows toward the tank 78 all day

 

[SebastianReefer]

My wife has a biocube 32 gallon and we live in Florida what I did was I took a half inch pvc coupler one for each side and used a dremel to make the notch where the lid is and propped up the lid and I have a fan across the room that blows toward the tank 78 all day

Oh and I don’t have any heaters on any of my 6 tanks

 

[AndyinAtlanta]

81 isnt bad per say, its 83 or more is where I start getting nervous.

Evaporative cooling capacity can be rather substantial, but will increase evap so an ato is a must.

How are you measuring your temperature if I may ask?

I have a digital thermometer in the tank, but I also have two kitchen instant-reads to check it against.

I'm thinking adding the fans to the lid would be the least invasive approach. I can mount two fans on the inside that exhaust out.

I just temporarily turned off the protein skimmer and powerhead and the temperatures are already dropping. The heat issues may be a result of the three motors running 24/7.

 

[AndyinAtlanta]

My wife has a biocube 32 gallon and we live in Florida what I did was I took a half inch pvc coupler one for each side and used a dremel to make the notch where the lid is and propped up the lid and I have a fan across the room that blows toward the tank 78 all day

Thanks! I like this idea. Right about now I wish I had a 3D printer to make it look nice but whatever.

 

[AndyinAtlanta]

I say do it now and avoid a potential disaster. If your AC unit ever goes out your tank will not stop at 82. I don't cool my home during the day as no one is home so my tank has 3 fans to cool it independently of what ever the room temperature is. Just a nice little backup and one less thing to worry about.

You can go down the powerhead rabbit hole but all pumps will heat the water, some more than others. The efficiency route is very costly.

Good point. I'm strongly considering cutting some holes and adding fans similar to what you'd do with a desktop PC.

 

[SebastianReefer]

Thanks! I like this idea. Right about now I wish I had a 3D printer to make it look nice but whatever.

Yea I don’t really like the look but we plan on getting rid of the lights it has, the old style bulbs and 4led strips, and putting either an AI or Radion cut the top take out the old fans and add bigger more powerful ones

 

[2Wheelsonly]

Yeah, I've considered the option of moving to a mesh top and upgrading the lights. That might be the best option. I'm pretty sure the heater isn't malfunctioning as the temperatures go up even when it is unplugged.

House is well over 120 years old, so no way I could get the temperature much lower living in the South. At 73 the AC is running almost all day.

I hear ya, I have a home that was built in the 70's and it was an absolute struggle to get it to 69 in the summer (winter is easy ). Good luck with whatever approach you take; this hobby has a way of challenging us at all times.

 

[Mrfish2020]

So I have the Fluval Flex 32.5 gallon saltwater tank, which is important to know because the tank's light is in the hood (and only an inch away from the water). I'd like to add a second light (same that came with my tank, I believe its the Fluval Marine 3.0), but I'm struggling with my tank's temperatures and I think its due to the heat from the light. Some additional variables that may be worth considering:

• The tank is not directly in front of any windows or diffusers
• The house temperature is set around 73 degrees
• I'm using the Fluval heater recommended for the tank.

I'd like the tank to sit at around 78-79 degrees, but no matter what I do it always creeps into the 80-81 range. The only time I can get it down to 78 is after a water change, but after two-to-three days it shoots back up to 80-81. The Fluval heater is set to 75 degrees so I'm guessing its barely ever on. I left the heater off for six hours today (with the light still on) and it gained .5 degrees over that period of time. I put an ice cube in the tank (in a plastic bag) and it briefly went down .2 degrees, but it was only temporary and it started going back up (again, no heater on).

I don't believe my tank is big enough to add a cooler, but I'm trying to determine the source of that much heat. I understand the pumps and lights generate heat, but so much that they render the heater irrelevant? I see a lot of posts about people trying to gain more heat, but I'm over here struggling to lose some of it.

How has this progressed for you. I Set one of these up in my apartment i noticed same issue. I am running stock equipment in the box plus the ps1 skimmer since July 13th 2020 cant keep it under 82c unfortunately my room temp currently is at 6:45 am pst is around 78c currently. I have no ac i plan to keep clown fish mostly